Unbeaten in 14 European fixtures at PSV Stadion, it was little surprise to see Fred Rutten's team demonstrate a composure their visitors lacked. As dominant as they were serene, PSV's buoyancy was typified no better than by the display of Mertens, whose 21st-minute strike proved the difference.

The Belgian international, boasting seven goals already for his club this season, went close three times inside the opening 20 minutes. It proved fourth time lucky midway through the opening period; Marcin Komorowski looked to have cleared the danger for Legia after shrewdly intercepting a through ball, but Mertens struck a splendidly instinctive strike from the left edge of the penalty area which whistled past Dušan Kuciak.

Yet to test Polish goalkeeper Przemysław Tytoń come half-time, Legia at least had their countryman scrambling six minutes after the interval, Komorowski's deft back-header drifting narrowly wide. Normal service soon resumed, however, as Mertens pulled the strings for PSV once more with a sumptuous cross from the left which Tim Matavž headed over.

Sharper and more inventive throughout, Rutten's men nevertheless struggled to rubber-stamp all three points. A handful of half-chances came and went, notably Stanislav Manolev's late dink which was well saved by Kuciak, but it mattered not, for the visitors – Jakub Wawrzyniak's meaty strike in the final minute aside – were unable to conjure up anything with which to concern Tytoń.

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